The 267 is used as the main amplifier in DC systems employing photodiode or photomultiplier detectors.

At low frequencies such devices give their best performance when connected to this type of virtual ground input.

The input effectively has zero input impedance and hence no voltage is generated across the device as a result of the photocurrent.

This short circuit operation enhances linearity of detectors and reduces the effect of cable capacitance.

Programmable dual inputs allow the use of pairs of detectors to increase the wavelength range of a scanning system.

Typical examples include pmt/Si, Si/Ge and Si/InGaAs.